This invention relates to a capsule made of disposable material containing a vaccine or medication dose to be hypodermically injected into the bodies of persons or animals through the use of a pressure injection apparatus. Once the capsule is put into use and the amount of liquid within the same is injected into the patient, the capsule is rendered useless so as to avoid reuse thereof, as in the case of the usual disposable syringes. Besides the fact that this capsule is previously filled with the correct dose of liquid to be injected, the major difference between it and the known means of hypodermic injection resides in that, in the case of the present invention, there is no needle to introduce said liquid through the skin. At the front portion of the capsule, there is only a very small orifice through which the liquid passes as a high velocity jet penetrating into the intradermic, subcutaneous or intramuscular tissues depending on the injector pressure. The major difference between the other pressure injector means and the present invention is that, in the present case, all the parts in contact with the medication are necessarily disposable after every application, since all these parts are contained within the capsule itself, which is self-destructive after use. In this sense, the only part which contacts patient's hypodermis at the injection location, that is, the nozzle itself with the orifice, is also an integral part of the capsule and therefore it is necessarily disposable after a single use. This definitively prevents any possibility of contamination from one patient to another, since every person would be necessarily vaccined with a new sterile nozzle.
Pre-sterilized disposable syringes are utilized worldwide in large scale and the practicability and safety thereof have been demonstrated for more than twenty years. However, disposable syringes and needles are often utilized twice or more by persons who aim at a great economy and utility of the product. For instance, this is the case of diabetic people who must take hypodermic injections daily and, not rarely, they use the same syringe and needle three times or more. Eventually, these persons put the disposable material into boiling water between use, since these materials are capable of sustaining one or two rapid contacts with boiling water. Reuse of disposable syringes, in this case, does not provide for the initial safety and sterility as guaranteed by the manufacturer in the tamper-proof package.
Nevertheless, this is not the major problem with disposable syringes since when they are used more than once by the same person, the hazards of infection are not too great, since contamination can only result from external media. Since there is an increasing diffusion of the use of injectable hallucinogenic drugs in our society, used disposable syringes came to be very sought after by drug consumers and frequently the same hypodermic needle is used many times by several persons without effecting intermediate asepsis. The hypodermic needle comes into direct contact with many individuals, therefore it is one of the most efficient ways of transmitting virus and bacteria from one person to another. In this way, cases of dissemination of blood-transmittable diseases, such as AIDS, have recently considerably increased by virtue of this reuse of disposable syringes and needles by drug users. This is now the most important problem in connection with these articles.
Since the past decade, this problem, has begun to be reflected by the inventions which have been developed aiming at improving the hypodermic injection methods or means that make use of disposable materials. Special attention has been drawn to ideas which suggested self-destruction after the first use. As typical examples of these ideas, one may cite the following patents: YERMAN (U.S. Pat. No. 4,233,975); CHIQUIAR (U.S. Pat. No. 3,998,224) and STAEMPFLI (U.S. Pat. No. 4,391,272). All these teachings disclose in one way or another the destruction of the syringe after use. On the other hand, however, these patents suggest a product which is more sophisticated and costly rather than inexpensible by virtue of being disposable. For this reason, practical commercial applications thereof have been quite limited.
Ideas have been developed for simple syringes without a movable piston and already containing therewithin the exact dose of medication to be injected. As typical examples, one may cite the following patents: CUNNINGHAM (U.S. Pat. No. 4,013,073) and MCALLER (U.S. Pat. No. 4,018,222). By utilizing these inventions, it would be enough to cause the needle to penetrate into the hypodermis and to squeeze with the fingers the medication flexible container. In this way, all the liquid would penetrate into patient's body through the needle and it is supposed that such container and needle would not be used again. However, even this type of syringe pre-filled with an individual dose may be reused. Although, at the expense of more labor than for the usual disposable syringes, refilling thereof can be done through the needle itself by suction from another container holding some other drug. Consequently, reuse of these products is possible.
On the other hand, the method of needleless pressure injection is also largely known and it has been employed in many countries for the last three decades. This method consists basically of putting a minute orifice in contact with a patient's skin so that a dose of medication is delivered through the orifice into the hypodermis under high velocity. Liquid is propelled against said outlet orifice by a piston generally actuated by a mechanism which biases and then releases a high compression spring. These hypodermic pressure injectors have been designed to render hypodermic injection more comfortable and to speed up the procedure of preparation and application thereof.
These injectors have been made simpler over time and presently they are used even individually by diabetic people to apply their own daily insuline dose. As a typical example of this situation, I can cite my own patent, LANDAU (U.S. Pat. No. 4,592,742).
However, recently, with the use of these hypodermic injectors in general public, suspicions have arisen that they also can disseminate transmittable diseases through blood. This suspicion derives from the fact that, upon receiving the liquid jet, a blood droplet can arise immediately at the site of application and this blood droplet could contaminate the orifice of the injector nozzle. This situation limits the utilization of pressure injectors for vaccination.
Therefore, it is understood that the only absolutely safe manner of avoiding blood contamination as caused by pressure injectors in vaccination campaigns would be that of using one new nozzle with the associated outlet orifice for every single person to be vaccined. That is, the nozzle with outlet orifice would be disposable and would have to be necessarily replaced after each application.